Single-phase alternating-current motor.



No. 811,644. PATENTE D FEB. 6, 1906.

B. G. LAMME. SINGLE PHASE ALTERNATING CURRENT MOTOR.

APPLIOATION FILED FEB. 27.1904.

Fig Y/.. Fly 2.

WITNESSES i or PITTSBURG. PEaxsrLvAlviA,

& MANUFACTURING COMPANY, A con PATENT OFFICE. 1

ASSlGNOR TO SINGLE-PHASE ALTERNATlNG-CURRENT MOTOR- Specification ofLetters Patent.

Patented Feb. 6, 1906.

Application filed February 2'7, 1904. Serial No. 195,684.

To a whom, it may concern.-

Be it known that I, BENJAMIN G. LAMME, a citizen of the United States,and a resident of Pittsburg, in the county of Allegheny. and State ofPennsylvania, have invented a new and useful Improvement in Single-PhaseAlternating-Current Motors, of which the following is a specification.

My invention relates to alternating-current single-phase motors; and ithas for its object to provide a self-starting inductionmotor of thisclass which shall be simple in construction and etlicient in operation.

Single-phase alternating-current motors having main primary windingsconnected directly to the distrilmtingdines and having auxiliarywindings of ditlerenttime constant from the main windings, which areconnected in parallel with the main windings in starting the motor, arewell known in the art. Yarious means have been employed for producing adill'erent time constant in the auxiliary winding from that in the mainwindin such a I c, k as resistance, rea'ctance, and capacity connectedin their proper relations with the said windings; but it has generallybeen found most expedient and economical to employ a comparatively highresistance either in the auxiliary winding itself or connected in seriestherewith.

Since the main winding has alarge amount of self-induction, the currenttherein lags considerably behind its electromotive force; but on accountof the dro in voltage in overcoming the resistance 0 the auxiliarywinding the current and electromotive force are but slightly displacedin phase therein. Hence the currents in the main and auxiliary windingsare out of phase with each other, and the motor at starting ispractically a polyphasemotor and conforms: to the laws governing thestarting conditions of such motors. The main winding only is used atspeeds approaching synchronism, and the motor becomes then asingle-phase machine. With such an arrangement of windings, however, thecur rent absorbed by the main winding in starting is excessive, and myinvention is designed to avoid this objection. It has been found ingle-phase motors that at or near half-speed a motor has considerabletorque and that if it could be brought up the operation of sintoapproximatelyhalf terminal 5;

speed in any way it could then be switched to the simple single phasecondition and would under normal conditions take up the load and pass tofull speed. In order to accomplish this, I have divided the main primarywinding into two portions or into two sets or groups of coils, which areconnected in series in starting the motor and in parallel for running,the current being reversed in one portion of the winding. The number ofpoles induced in the primary member with the two portions of the windingin series is double the number corresponding to parallel connection ofthe two portions of, the winding. The function of the auxiliary windingremains the same as for the simple case before described, the number ofpoles induced thereby being equal to the number of poles induced by themain winding when its two portions are connected in series or as forstarting conditions.

It may be arranged as desired to manually or automatically cut theauxiliary winding out of circuit and connect the two portions of themain winding in parallel for the smaller number of poles after the motdrhas attained approximately half-speed or the full speed corresponding tothe series connection of the two portions of the main winding. Inasmuchas the motor has a low starting torque, it may sometimes be foundnecessary to bring it up to approximately full speed before connectingit to its load, which may be done by any suitable means, such as a loosepulley and clutch operated either manually or automatically bycentrifugal force.

In the accompanying drawings, Figure 1 is a diagrammatic view of themotor-windings arranged and connected for starting conditions of themotor; and Fig. 2 is a similar view showing the windings as arranged andconnected for running conditions of the motor, both in accordance withmy invention.

A A and B B are the terminals of the two portions of the main primarywinding which are respectively connected with the contactterminals 1, 2,3, and '2 of the double-throw sw tch 4, and C O are the terminals of theauxiliary primary winding which are respec tively connected with thecontact-terminals 1 and 5 of the said switch. An external resistanceelement R is included in the connection between the terminal C and thecontactbut, as before stated, this resist ance may be omitted it theauxiliary wind tact-terminal 1 so that the resistance is in the windingitself. The three-pole double-throw switch 4 represents a simple meansfor governing the circuits of the primary windings of the motor; but anyother suitable device may be employed, if desired.

. an auxiliary winding In Fig. 1 the switch is shown in proper psi"sition or connecting the primary windings for starting conditions of themotor or such that the two portions A A and B B of the main primarywinding are connected in se ries, and the number of magnetic polesinduced thereby is 2 the circuit through them being from the lineconductor L through the switch-blades 7, contact-terminal I, winding A rwinding B B, contact-terminal 3, and switch-blade S, to the lineconductor L The circuit of the auxiliary winding iis from line conductorL, through switch-blade '1', conwindings C C, resistance R,contact-terminal 5, switch-blade 9, and contact-terminals 10 and 11, tothe line conductor U, the number of poles induced by this winding beingalso 2 In Fig. 2 the switch is shown in position for connecting theprimary windings inparallel, the current in the winding B B beingreversed in direction l'r om that shown in Fig. 1, and the number ofpoles being thereby changed from 2* to X. The auxiliary winding and itsresistance R are also thrown out of circuit, so that the motor nowbecomes a simple single-phase machine. Single-phase currents aresupplied to the primary windings by means of the circuit from the lineconductor L, through the contact-terminal 12, switch-blade 7,contact-terminal 1, winding A A, contact-terminal 2, switch-blade 9 andcontact-terminals 10 and 11, to the line conductor U, and the parallelcircuit from L, through contact-terminal 13, switch-blade 8,contact-terminal 3, winding B B, contac terminal 2, switch-blade 9, andcontact-terminals 10 and 11, to theline conductor L The secondary member14 of the motor may be of the ordinary squirrel-cage type ofconstruction or of any other well-known type.

I claim as my invention 1. A single-phase induction-motor having a mainprimary winding comprising two portions, means for connecting saidportions in series for starting and in parallel for running and at thesame time changing the number of magnetic poles produced by said windingand having a different time constant from that of the main winding.

2. A single-phase induction-motor having a main primary windingcomprising two portions, means for connecting said 'ortions in seriesfor starting and in parallel or running and at the same time changingthe number of magnetic poles produced by said winding and an auxiliarywinding having a different time constant from that-of the main windingand adapted to produce the same number of magnetic poles as the mainvwinding under starting conditions.

3. A single-phase induction-motor having a main primary windingcomprising two portions, means for connecting said portions in seriesfor starting and in parallel for running and at the same tim changingthe number of magnetic poles produced by said winding and an auxiliarywinding having a different time constant from that of the main windingand ,connected in parallel therewith for starting and which is adaptedto produce the same number of magnetic poles as the main wind ing understarting conditions.

i. A singlephase induction-motor haying a main primary winding comprisng two portions, means for connecting said portions in series forstarting and in parallel for running. the number of magnetic polesproduced by said winding being thereby changed irom 2" to X, and anauxiliary winding having a di'l- 'ferent time constant from that ofthemain winding and adapted to produce 2 magnetic poles under startingconditions.

5. A single-phase induction-motor having a main primary windingcomprising two portions, means for connecting said portions in seriesfor starting and in parallel for running,

the number of magnetic poles produced by said winding being therebychanged from 12 to I\, and an auxiliary winduig having a (iIfferent timeconstant from that of the main winding, in parallel with which it isconnected for starting, and adapted to induce 2 magnetic poles.

In testimony scribed my 1904.

whereof I have hereunto subname this 12th day of February,

HENJ. G. LAMME. Witnesses:

Eusann'rn M. STEWART, BIRXEY HrNEs.

IOO

